The development of transponder technology is rapidly accelerating to meet high data rate needs of next-generation optical carrier networks. Emerging transponders may, for example, use multi-level Dual Polarization Quadrature Phase Shift Keying (DP-QPSK) modulation schemes to improve optical spectral efficiency. The emerging transponders may include multiple radio frequency data input ports that utilize multi-channel modulator drivers. The multi-channel modulator drivers may be positioned such that radio-frequency (RF) emitting components associated with different channels interfere with one another (e.g., cross-channel coupling). Techniques and configurations to isolate the channels and reduce such interference may be desirable.